Oregon Utility Is Farmers’ Friend, Turning Manure Into Power

A dairy farm in the western United States is the latest beneficiary of a growing technological solution to eliminating farm manure by turning it into electricity.

SALEM, Oregon, US, 2001-12-12 [SolarAccess.com] Portland General Electric has built an anaerobic digester on the Cal-Gon dairy farm in Salem, to convert 40 tons of cow manure each day into energy, providing 100 kW of electricity for the grid. The manure from 400 cows goes into a 28 foot digester where it releases methane gas, which then fires a generator. Leftover materials are processed through the solids separator machine into relatively odour-free fibre and liquids (10 cubic yards of fibre and 9,000 gallons of liquid fertilizer per day) that can be used for commercial nursery or farm soil applications. In addition to the small-scale Cal-Gon plant, PGE is developing a large farm project in eastern Oregon at Threemile Canyon Farms LLC. On 45,000 acres near Boardman, this cropping farm will operate three dairies with 6,800 cows each. Methane produced from these operations will generate 4 MW of green power, enough to light the homes of 2,500 customers, starting next summer. PGE expects the system will be cost-competitive with other renewable resources such as wind turbines that currently provide the utility with 250 kW, or one percent of its power. The utility will receive a 35 percent tax credit spread over five years from the Oregon Office of Energy for investing in alternative energy technologies, and PGE will sell the methane-derived power at a premium rate for green energy. The utility recently lowered its green power prices by 30 percent with a 100 kWh block now costing US$3.50 per month, down from $5 because of improved markets for electricity generated by wind turbines. Livestock manure management has affected the growth of the dairy industry, but biogas facilities give producers more flexibility in manure disposal, reducing odour and the need for commercial fertiliser, and potentially increasing herd size. With 400 dairy farms in Oregon, the state’s Dairy Farmers Association and the Department of Agriculture are optimistic about the potential for biogas to help the industry, the economy and the environment. Anaerobic manure digestion attracted interest during the energy crisis of the 1970s, but most failed because farmers were not trained how to run the complex machinery, and interest waned as energy prices dropped. Currently, there are only 30 manure digesters on commercial livestock farms across the U.S. with half on dairy farms, according to the EPA, although large contracts have been signed to turn pig manure into biogas from large farms in the east that face tough environmental controls. Dairy farmers say the methane digesters will help them comply with stricter federal regulations that will limit phosphate levels in the soil. The partnership between the Oregon Dairy Farmers Association and PGE marks the first time that a utility has coordinated with farmers to develop an economically feasible digester at the utility’s expense, and PGE plans to build experimental digesters at two more Oregon dairies next year. Requests have come from farmers as far away as New Mexico in response to news about the PGE project. “The PGE BioGas Program increases the supply of electricity through the effective use of a renewable resource, helping limit our reliance on finite supplies of natural gas,” says the company’s director of distributed resources Joe Barra. “At the same time, it reduces air pollution and gives an important boost to the dairy industry.”

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